


Vol 37, No 10 (2017)
- Year: 2017
- Articles: 19
- URL: https://journal-vniispk.ru/1068-798X/issue/view/14014
Article
Control system for the Stirling engine
Abstract
A new control system is proposed for Stirling engines. The system is based on a sealed external system for hydrogen sorption and desorption, with a thermoelectric heating and cooling system. It is intended to improve the operational reliability and the safety of the maintenance crew; to reduce the operational noise level; and to reduce the size and mass of the motor and simplify its design.



Dynamic characteristics of pressure regulators with elastic shutoff valves
Abstract
The dynamic characteristics of a pressure regulator (a direct-action safety valve) are investigated. A regulator with a shutoff valve made of elastic material and reinforced by an elastic spring is described. The phase-trajectory method is used to establish the parameters of the regulator and the conditions in which it operates stably.









Transfer films in a PTFE–steel pair at different temperatures
Abstract
The wear of the polytetrafluoroethylene–steel frictional pair is investigated. The dependence of the frictional coefficient and the wear on the contact temperature is determined. The temperature range of adhesive wear is established for polytetrafluoroethylene.



Fatigue failure at low temperatures
Abstract
The fatigue failure of steel 20 at low temperatures is considered. Strain hardening of the surface layers is found to occur in adiabatic conditions at low temperatures. That increases the fatigue strength. Fatigue cracks form and grow along the grain boundaries. The influence of impurities on the fatigue failure of low-carbon steel is studied.






Improving the performance of high-strength steel castings by specialized cooling
Abstract
The influence of microcooling and external cooling on the structure and mechanical properties of moderately alloyed high-strength special-purpose steel and also on the morphology of its nonmetallic inclusions is investigated. The properties of castings obtained in different molds and in different conditions are compared. The influence of hybrid (external and internal) modification of the casting process on the quality of heavy housing castings is investigated.



Wear resistance of cutting tools with a plasma-modified surface layer
Abstract
An analytical model is obtained for calculating the working life of a cutting tool with a plasmamodified surface layer. It permits calculation of the conditions ensuring increased wear resistance of the tool and hence increased reliability in manufacturing on numerically controlled machine tools.



More precise determination of the cutting forces at the tool’s rear surface
Abstract
Two methods have been proposed for more precise determination of the cutting forces when using tools with different wear at the rear surface: in one, the actual contact is taken into account; in the other (proposed by Zorev), it is ignored. In the present work, these methods are compared.



Monitoring system for high-tech equipment
Abstract
Many organizations and automated data-processing systems are involved in analysis of the logistical support (ALS) of high-tech equipment. Therefore, the initial data and the results of analysis must be presented in standardized form. That calls for an integrated informational model describing all the relevant data elements, their attributes, and their relationships. In ALS, the instruments that monitor the operation of the high-tech equipment form an important component of the information system.



Regulation of the machining precision by programmed tool correction
Abstract
On the basis of a mathematical model of a machining center, a method of programmed correction of the tool and workpiece motion in numerically controlled metal-cutting machines is proposed. This method improves the machining precision in real time.









Copper-coated electrodes for electrical discharge machining of 38X2H2MA steel
Abstract
The use of copper-coated aluminum electrodes in the electrical discharge machining of 38X2H2MA steel is assessed. Such electrodes prove effective. The use of coated electrodes improves the economics of electrical discharge machining by permitting the use of cheaper materials in the electrode core.









Composites with improved absorption of noise and vibration
Abstract
The development of composites based on thermosetting resins with improved vibration and noise absorption is considered. Mathematical and topological models are proposed to describe the influence of the composition on the vibration and noise absorption and elastic properties of the composites. The composition of filled epoxy, polyester, and polyurethane vibration-absorbing composites is optimized in terms of their loading, dynamic, and economic characteristics.



Glass-filled polyurethane materials produced by fiber composite spraying
Abstract
By using polymer composites in auto parts, the vehicle mass may be considerably reduced, with improvement in the dynamic properties and load capacity of the vehicle and also in its fuel consumption and tailpipe emissions. In the present work, recommendations are made for improving the performance of glassfilled polyurethane materials produced by fiber composite spraying. To that end, the thermal stability, impact strength, high-temperature strength, and Shore D hardness are determined in accordance with Technical Specifications TU 2292-010-14682925–2014. The sound absorption and UV resistance of the composites are also determined.


